The present invention relates to a pallet changer suitable for use with a machine tool.
A flexible manufacturing system (FMS) comprises a machine tool and a pallet changer. The pallet changer exchanges a pallet set on the table of the machine tool for another pallet. The conventional pallet changer has an exclusive hydraulic cylinder or chain drive for moving a pallet.
In the pallet magazine of a hydraulic type, a pallet is moved on the table of the machine tool by a hydraulic cylinder. Once a machining operation on a workpiece set on the pallet is completed, the pallet is moved away from the table by the hydraulic cylinder.
In the pallet magazine of a chain type, a plurality of pallets are set on the chain at the same intervals. The chain is driven by a motor and the pallet is indexed in front of the table of the machine tool.
A pallet and a workpiece are considerably heavy. Therefore, a large hydraulic cylinder, a large driving motor and a heavy chain are required. Such a pallet magazine is large in size and has a complicated structure.
On the other hand, in case the pallets and the works are driven by such a large hydraulic cylinder or a driving motor, they are inevitably shocked because of a large inertial force. To carry the pallet and work without shock, the large hydraulic cylinder or the large driving motor must be operated very slowly. Thus, it takes a lot of time to exchange pallets.